1. Field of the Invention
This invention relates to systems for space heating and cooling and, more particularly, to such systems which are heat actuated and function as heat pumps.
2. Description of the Prior Art
Heat pumps have long been used for efficiently transferring heat from one medium to another, thus permitting the heating or cooling of a given space with the heat being transferred from some readily available medium (ambient air, water in an adjacent lake or well, a body of rocks or salt, or the like) for heating, and being delivered to the medium (often the same body of water, etc.) for cooling.
For example, the Carleton U.S. Pat. No. 3,135,318 describes a heat pump system using a turbo-compressor which provides power and waste heat to a standard vapor cycle refrigeration system. Two turbines are employed in the system, one driving the turbo-compressor and a second turbine driving a recirculating air fan and the refrigerant compressor.
The Miller U.S. Pat. No. 3,822,561 describes a self-contained, portable air cooling unit comprising a refrigeration circuit, a thermal reservoir consisting of an ice bank in a flexible tank, and a heat exchanger for transferring heat between the air in the space to be cooled and chilled water circulated from the ice bank and reservoir. Means are provided to selectively and alternatively operate the refrigeration circuit and the circulating system to heat or to cool the space as desired.
The Lodge U.S. Pat. No. 3,407,620 describes a system for heating and cooling using a recirculating water loop. Heating is supplied by a standard heater using combustible fuel, and cooling is provided by a cooling tower. Although the patent represents the system as a heat pump, it is not a heat pump by the usual thermodynamic definition.
The La Fleur U.S. Pat. No. 3,355,903 describes a closed reverse-Brayton-cycle refrigeration system to prvide refrigeration for air liquefaction. Repetitive stages of compression and cooling are employed.
A heat-actuated space conditioning system utilizing a Brayton engine is described in an article entitled "Light Commercial Brayon/Rankine Space Conditioning System" by David Friedman, beginning at page 172 of the August, 1977 Proceedings of the 12th IECEC (Intersociety Energy Conversion Engineering Conference). This article describes a Brayton cycle system utilizing a combustor driving a turbo-compressor, the latter being magnetically coupled to a second compressor in an associated Rankine cycle system.
The Linhardt et al U.S. Pat. No. 3,902,546 describes a system utilizing a gas turbine driving a Freon compressor for refrigeration with an air cycle heat pump connected to the Freon cycle through a hydraulic coupling which permits decoupling at different parts of the operating cycle.
The Dennis et al U.S. Pat. Nos. 3,400,554 and 3,487,655 describe equipment using a Rankine power cycle in a Freon air conditioning system. A turbine and a compressor are coupled together through a magnetic coupling incorporating a stationary impervious membrane between the rotating components of the coupling for sealing purposes.
U.S. Pat. Nos. 2,309,165 of Candor and 3,139,924 of Schreiner describe systems utilizing internal combustion engines driing a Rankine cycle heat pump. U.S. Pat. Nos. 2,471,123 of Rouy and 2,409,159 of Singleton describe air conditioning systems similar to those which are currently configured on present day aircraft. The Rouy patent device uses a Brayton power cycle integrated with a bootstrap compressor to power the unit, once it is started. These systems can be used for either heating or cooling.